A prior art network-unit forms part for example of an asynchronous cell switching system, and makes use for example of an internal flow control mechanism like for example an internal dynamic rate-based flow control mechanism, whereby multicast copies are for example generated in an input termination module. Buffers in such an input termination module are structured with per-virtual-ingress-egress-pipe queues and are controlled by a per-virtual-ingress-egress-pipe rate-based scheduler-spacer. Such a network-unit efficiently switches various traffic types, like quality-of-service and non-quality-of-service guaranteed bursty traffic.
The known network-unit is disadvantageous, interalia, due to relatively inefficiently handling multicast messages: multicast copies are merged into the per-virtual-ingress-egress-pipe queue and are scheduled in the per-virtual-ingress-egress-pipes. For relatively large numbers of multicast cells/groups (multicast cells and/or multicast groups), this approach takes relatively much time.